1. Field of the Invention
This invention relates generally to interfacing electrical components, and, more particularly, to a method and apparatus for interfacing electrical components operating at different voltage levels.
2. Description of the Related Art
Over time, manufacturers of integrated circuits have been able to place more and more circuitry on less and less real estate of a semiconductor chip. The ability to place more circuitry on an integrated circuit chip is a function of at least the size of the components constructed on the chip and the spacing between components (i.e., density). Reductions in size and spacing have allowed the use of lower voltage levels to properly operate an integrated circuit.
Operating integrated circuit chips at reduced voltages has inherent advantages. For example, lowered operating voltages allow even densely packed integrated circuit chips to operate at relatively low temperatures, such that exotic cooling methods are not required. Moreover, using lower voltages reduces power consumed by an integrated circuit chip, which is of particular significance in battery-operated devices, such as portable computers.
A disadvantage of operating an integrated circuit chip at a reduced voltage is that an integrated circuit chip is commonly required to interface with a variety of existing integrated circuit chips that operate at a higher voltage level. Thus, when a reduced voltage integrated circuit chip is used as part of a larger system, it will likely be required to receive interface signals at these higher voltage levels. Often, these interface signals are digital in form, and must be able to transition between their logically high and low states within a relatively short, preselected period of time. Heretofore, signal conditioning circuitry used to translate from these higher voltage levels to the lower voltage levels has adversely affected the transition time period, and thereby reduced the performance of lower voltage integrated circuit chips. A slower transition time means that a receiving circuit must wait longer to ensure that the signal has stabilized before the signal can be accessed. Thus, slower transition times translate to slower overall operating speed.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.